Variable delivery fan



Sept. 19, 1967 R. MARTIN VARIABLE DELIVERY FAN 2 Sheets-Sheet 1 Filed June 1, 1966 )NVENTOR ROBERT 1.. A/lART/N ATTORNEYJ Sept. 19, 1967 MARTIN 3,342,272

VAR IABLE DELI VERY FAN Filed June 1, 1966 2 Sheets-Sheet 2 /N VENTOR ROBERT L. MART/N 4 TOR/V5 United States Patent 3,342,272 VARIABLE DELIVERY FAN Robert L. Martin, Detroit, Mich, assignor to Eaton Yale & Towne Inc., Cleveland, Ghio, a corporation of Ohio Filed June 1, 1966, Ser. No. 554,406 12 Claims. (Cl. 170-160.].1)

The present invention relates in general to a variable delivery fan, and more particularly to a variable delivery fan having fan blades mounted on a support member and capable of moving relative to the support member to move different amounts of air.

An object of the present invention is the provision of a new and improved fan mechanism which provides a flow of air for cooling purposes and which is effective to provide a desired amount of cooling air which corresponds to cooling requirements both at high and low fan speeds.

Another object of the present invention is the provision of a new and improved fan mechanism operable to provide a flow of air and wherein the fan mechanism includes blades movable between a position providing a maximum flow of air and a position providing a substantially smaller flow of air and wherein the blades are movable between their positions in response to the temperature of the air.

Still another object of the present invention is the provision of a new and improved fan mechanism for providing a flow of air and wherein the fan mechanism includes means for effecting movement of the blades of the fan between a radially extended position and a radially retracted position, wherein the fan provides substantially different flows of cooling air at a given fan speed, and wherein the means for effecting movement of the blades includes a member movable in opposite directions to effect movement of the blades between their positions.

Yet another object of the present invention is the provision of a new and improved fan mechanism wherein the fan includes blade means which are movable relative to the fan between a postiion providing for a first flow of air and a position providing for a second smaller flow of air with the blade means moving between their positions in response to centrifugal force about an axis and wherein the centers of gravity of the blade means is shifted relative to the axis to effect movement of the blade means between the postiions.

A further object of the present invention is the provision of a new and improved fan mechanism, as noted in the next preceding paragraph, wherein the blade means includes a weight member shiftable relative to a blade member thereof in response to temperature changes to thereby move the center of gravity and effect movement of the blade means.

A still further object of the present invention is the provision of a new and improved fan including a support member and blades which are pivotally movable relative to the support member and about axes substantially on their respective centers of gravity to provide differing flows of air at a given fan speed, and wherein each blade is moved between its positions by a reciprocable member connected with the blade and reciprocated by a temperature sensing device.

Further objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments thereof made with reference to the accompanying drawings which form a part of this specification and wherein:

FIG. 1 is an elevational view of a fan mechanism embodying the present invention;

FIG. 2 is a fragmentary view of a portion of the fan mechanism of FIG. 1 shown on an enlarged scale;

FIG. 3 is a sectional view of the fan mechanism of FIG. 1 taken approximately at line 33 of FIG. 1;

FIG. 4 is an elevational view of a modified fan mechanism embodying the present invention;

FIG. 5 is a sectional view taken approximately at line 5-5 of FIG. 4; and

FIG. 6 is an enlarged fragmentary sectional view of a portion of the fan of FIG. 4.

The present invention provides an improved fan having a support member and fan blades which are supported for movement between two positions relative to the support member. One position of the fan blades provides a maximum amount of air flow at a given speed, while at the other position the air flow created is lower than it would be had the blades not been moved. Such a fan is particularly useful in an automotive vehicle as an engine cooling fan since the amount of cooling air required by the engine varies in response to the engine cooling requirements. As representing a preferred embodiment of the present invention, a fan A for use in an automotive vehicle is illustrated in FIG. 1.

The fan A comprises a rotatable support member 10 mounted on a shaft 11 for rotation therewith and fan blade assemblies 12 connected to the support member 10 so as to be rotatable with the support member and movable with respect thereto. The support member 10 includes a hub portion 13 which is fixedly secured to the shaft 11 by means of a connecting member 14 having a collar portion surrounding the shaft 11 and a flange portion bolted to the hub portion 13. A plurality of arms 15 extend radially from the hub 13 at spaced intervals on the circumference of the hub. Each arm 15 carries a fan blade assembly 12 thereon located near the outer radial end thereof. The fan blade assemblies 12, upon rotation of the support member 10, produce a flow of air in an amount which is dependent upon the position of the assemblies on the support member and the fan speed.

The fan blade assemblies 12 each include a fan blade 17 which is movable relative to the support member 10 to provide a flow of air which depends upon the position of each blade 17 relative to its support arm 15. More specifically, each fan blade 17 is capable of pivoting about an axis parallel to the axis of rotation of the shaft 11 between a position in which the longitudinal axis of the fan blade is generally radially directed, as shown in dotted lines in FIG. 2, and a position where the longitudinal axis of the fan blade is generally tangentially directed, as shown in full lines in FIG. 2. When the fan blades are in a position where their longitudinal axes are generally radially directed as shown in dotted lines in FIGS. 1 and 2, the air through which the blades pass, upon rotation in the direction indicated by the arrows in FIGS. 1 and 2, is acted upon by front and back surfaces 18, 19, respectively, of the blades in a well-known manner to produce a flow of air axially of the fan and in the direction of the arrow in FIG. 3. In this position the fan blades produce a maximum flow of air for a given speed of rotation thereof.

When the fan blades are in their positions where their longitudinal axes are directed generally tangentially to the circle of rotation, as indicated in full lines in FIGS. 1 and 2, the air through which the blades pass crosses the surfaces 18, 19 of the blades generally along their longitudinal axes so that the fiow producing interaction between the air and surface 19 is at a minimum for a particular fan speed and the blades 17 produce a minimum flow of cooling air for the engine. Moreover, since the radial extent of the blade is small in this position, the tip velocity of the blade is minimized accordingly, and the fan blades in this position produce a minimum amount of noise for a given fan speed.

The fan blade assemblie 12 including the fan blades 17 and their mode of connection to the arms 15 for movement relative thereto are identical and, therefore, only one fan blade will be described with its mode of connection to its associated arm. Each fan blade 17 has generally concentrically curved side edges 21, 22 extending in a general direction of the longitudinal axis of blade 17 and joined by end edges 23, 24 forming generally lobular end portions. The fan blade 17 is curved in a direction generally transverse to its longitudinal axis shown in FIG. 3. The front surface 18 has an indent 25 extending generally along the longitudinal axis thereof which indent is formed by walls 26, 27. The indent 25, as illustrated, extends slightly more than half of the length of the fan blade, and when the fan blade 17 is in it radially extended position, the associated arm 15 is nested in the indent 25.

Each fan blade 17 is connected for pivotal movement relative to its respective arm 15 approximately at the center of gravity of the blade. The connection between the blade 17 and the arm 15 is effected by a bolt 30, which extends through aligned openings in the arm 15 and blade 17, and a nut 31 which is threaded on the bolt to secure the arm 15 and blade 17 together. A pair of washers 32 are disposed about the bolt 30 on opposite sides of the arm 15 so that the blade 17 is freely movable relative to the arm 15 about the axis of the bolt 30. The head portion of the bolt 30 is provided with means for holding the bolt 30 against rotation relative to the blade 17. Any suitable anti-rotation construction may be used for this purpose. The washer- 32 are effective to permit rotation of the blade 17 and the nut and bolt relative to the arm 15.

In accordance with the present invention, means is provided which is effective to shift the center of gravity of the fan blade assemblies 12 so that centrifugal forces resulting from rotation of the fan move the blade 17 relative to the arm 15 between its positions of maximum and minimum air flow. As shown in FIG. 2, temperatureresponsive means 40 are provided to effect shifting of the center of gravity of each blade assembly 12. Each temperature-responsive means 40 is connected to the bolt 30 and is effective, upon changes in temperature of air passing across the blade 17, to change the center of gravity of the blade assembly 12, as described, to move the blade 17 between its maximum and minimum flow positions.

The temperature-responsive means 46 forms a part of the blade assembly 12 and includes an outer casing or shell member 41 having end portions 42, 43 rigidly secured at the ends thereof and an expansible chamber element or power element 44 located within the shell and between the end portions 42, 43. The power element 44 includes a body'portion 45 and a piston element 46 located in a cavity in the body portion 45. The piston 46 abuts a support member 47 which is disposed along an inner wall of the shell 41 and resiliently supported against axial movement relative to the shell 41 by an annular plastic ring member 48. The member 48 is held between the support member 47 and the end portion 43 of the shell. The body portion 45 of the power element 44 is biased toward the end portion 43 by a spring 50 which is supported by the end portion 42 of the shell 41 and abuts an annular flange 51 formed on the body portion 45. The piston 46 is slidably supported in the body portion 45 and the cavity in the body portion 45 contains an expansible fluid-like substance, such as a thermostatic wax intimately mixed with a finely divided heat-conducting material, or other suitable material, which is adapted to expand and contract a substantial amount in response to temperature changes. For a more detailed description of a power element similar to that illustrated herein, reference is. hereby made to United States Patent No. 2,368,181, issued January 30, 1945.

As air temperatures decrease, the wax or thermostatic fluid in the expansible chamber member contracts so that the spring 50 moves the body portion 45 toward the end portion 43 of the casing or shell 41. Upon increases in temperature of the thermostatic fluid, the piston member 46 is urged out of the body portion 45 resulting in movement of the body portion 45 against the bias of the spring and toward the end portion 42 of the casing 41. The temperature-responsive means 46 is shown in FIG. 3 in its fully extended or high temperature position.

The temperature-responsive means 40 forms an integral part of the fan blade assembly 12 and is connected thereto by a suitable connecting means such as a band 52 which is suitably secured to the head of the bolt 30 such that the temperature-responsive means 40 is fixed against movement relative to the fan blade 17. It should be apparent that the bolt 30, blade 17, and temperature-responsive means 40 form an integral blade assembly r0- tatable about the axis of the bolt 30 relative to the arm 15 between a maximum air delivery position of the blade and a minimum air delivery position of the blade.

The temperature-responsive means 40 is oriented with respect to the blade 17 so that when the blade is in its radially extended or maximum delivery position, as indicated in phantom lines of FIG. 2, the longitudinal axis X, see FIG. 2, of the temperature-responsive device lies generally perpendicular to a radial line Y extending from the axis of rotation of the hub 1 and the axis of rotation of the bolt 30. When the blade is in its radially retracted or minimum delivery position, as indicated in solid lines in FIG. 2, the longitudinal axis of the temperature-responsive means 40 lies on a line extending approximately 15 degrees from the aforementioned radial line Y. It will be seen then that the blade in its pivotal movement about the axis of the bolt 30 pivots through an angle of approximately 75 degrees between its position of minimum delivery and its position of maximum delivery.

When the blade 17 is in its position of minimum delivery as shown in solid lines in FIG. 2 and the fan A is rotated, the blade will be maintained in its minimum delivery position until such time as the temperature of the air passing across the blade i suificient to cause the body portion 45 of the temperature-responsive means 40 to move and thereby change the center of gravity of the fan blade assembly 12. When the blade is in its retracted position and the temperature of the air through which the blade assembly moves is at or below a predetermined temperature, the center of gravity of the power element is located on the pivot axis of the blade assembly or to the left of the pivot axis along the line B, as viewed in the drawings. When the center of gravity of the power element is located as described, the blade 17 is maintained in its retracted position. As the air temperature increases, the center of gravity of the power element 44 shifts along the line E and to the right of the pivot axis of the blade assembly 12, as viewed in FIG. 2, and to a point S. As the center of gravity of the power element shifts, the center of gravity of the blade assembly 12 shifts, and centrifugal forces due to the rotation of the fan A rotate the fan blade assembly in a counterclockwise direction relative to the arm 15 and to the maximum delivery position of the blade 17. Further rotation of the blade in a counterclockwise direction is prevented by engagement of the arm 15 with the wall portion 26 with the indent 25 formed in the blade 17 When the blade 17 is in its maximum delivery position, the longitudinal axi of the power element 44 lies along the line X. Further increases in air temperature move the center of gravity of the power element along the line X and to the right of the pivot axis of the blade 17 so that centrifugal force acting on the blade assembly continues to urge the blade assembly toward its radially extended position.

The blade 17 remains in its maximum delivery position until the temperature of the air is decreased sufliciently to permit contracting of the expansible material in the expansible chamber member 41, whereupon the center of gravity of the power element shifts along the line X to a point M to the left of the radial line Y extending through relatively low temperature. These the pivot axis of the blade assembly. When the center of gravity of the power element shifts, as described, the centrifugal force acting on the blade rotates the blade clockwise relative to the arm 15 to return the blade 17 to its minimum delivery position. Movement of the blade 17 past its position of minimum delivery is prevented by engagement of the arm 15 with the side wall 26 of the indented portion 25. When the blades 17 of the fan A are in their radially retracted or minimum delivery position, the blades 17 form a generally circular band about the axis of rotation of the fan A to provide a fan configuration which may be termed a toroid.

It should be noted that the movement of the body portion 45 in response to temperature changes may be very small in order to effect rotation of the blade 17 about its pivot axis, since the centrifugal forces developed upon rotation of the fan A provide an extremely large force acting at the center of gravity and about the pivot axis. A fan constructed in the manner shown in FIG. 1, for example, might include fan blades having a static weight of 0.39 lb., but when the fan is rotated at 2500 r.p.m., each blade has adynamic wei ht of 400 lbs. In actual practice, movement of the expansible chamber element is preferably on the order of approximately 0.100 inch, which movement is suflicient to cause the fan blade 17 to move between its maximum and minimum delivery positions. This has been exaggerated in the drawings for explanatory purposes.

The mode of operation of the fan A should be clear from the above description. When the fan is rotating at a given speed, and the engine cooling requirements are low, the air crossing the blades of the fan is generally of a relatively low air temperatures are effective to maintain the center of gravity of the blade assembly 12 on the pivot axis of the blade 17, or at a point radially outward and to the left of the pivot axis of the blade, as viewed in FIG. 2. In this position, the fan will move a minimum amount of air through the radiator and across the engine as described above. When cooling requirements of the engine increase, the temperature of the air passing across the fan blades will, of course, be increased to move the center of gravity of the blade assembly 12 radially inwardly and to a position located generally to the right of the pivot axis of the blade, as viewed in FIG. 2. When the temperature is increased sufliciently to move the center of gravity to the right of the pivot axis of the blade, centrifugal forces developed by rotation of the fan A produce a pivoting moment tending to rotate the blade from its minimum delivery position in a generally counterclockwise direction to its maximum delivery position.

When the blade 17 has been moved in a counterclockwise direction toits maximum delivery position, the arm 15 engages the wall portion 26 of the indent in the blade 17 such that further movement of the blade in a counterclockwise direotion is prevented and a maximum flow of air is provided by the blade 17. Additionally, the center of gravity of the blade is moved to the right of theaxis of rotation of the blade 17 so that as fan speed increases, the pivoting moment will increase and tend to hold the blade 17 in its maximum delivery position. This moment is effective at high speeds of rotation of the fan A to prevent aerodynamic forces, created along the leading edge of the blade as the fan rotates, from moving the blade from its maximum delivery position to its minimum delivery position.

When the blade is in its maximum delivery position and the engine cooling requirements are decreased, the temperature of the air passing across the blade 17 is, of course, decreased accordingly and the body portion 45 moves in response to the temperature changes to shift the center of gravity of the power element 44 to the left of the pivot axis of the blade 17, as viewed in FIG. 2. When the center of gravity of the blade 17 has been moved to the left of its pivot axis, the centrifugal forces acting at the center of gravity move the blade 17 in a generally clockwise direction and rotate the blade 17 about its pivot axis to return the blade 17 to its minimum delivery position.

FIGS. 4, 5 and 6 illustrate a modified fan B embodying the present invention. The fan B is driven in a clockwise direction as viewed when looking toward an engine, which has not been shown, and includes a hub or support member 60 which is connected by suitable means to a drive shaft of the engine. The hub or support member 60 includes fan blades 61 which are pivotally mounted on arms 62 which extend radially from the support member 60 such that the blades are rotatable with the support member 60 and pivotally movable with respect thereto about an axis which is normal to the plane of rotation of the support member.

The support member 60 is a one-piece, disc-like member which includes a rearwardly extending wall 64 which is connected to a radially extending flange 65. The flange 65 is formed integrally with the arms 62 upon which the fan blades 61 are mounted.

The fan blades 61 and their connection with the support member 60 are identical in construction and therefore only one fan blade will be described with its connection with the support member 60. The fan blade 61 is formed from a thin sheet of light metal material and has the shape and configuration of the blades described hereinabove in reference to FIGS. l3. The blades 61 is pivota-lly connected to the arms 62 by a conventional connecting means which may correspond to the connecting structure shown and described hereinabove in reference to FIGS. l3, however, any other suitable connecting means could be used. The fan blade 61 is movable between a position wherein the blade delivers a minimum flow of air for a given speed of rotation of the fan B, as shown in solid lines of FIG. 4, and a position wherein the blade delivers a maximum flow of air at a given speed as shown in phantom lines of FIG. 4. The blade 61 moves between its positions of minimum and maximum air delivery as a result of pivotal movement about an axis of the connecting means between the blade 61 and the arm 62 and which axis extends generally parallel to the axis of rotation of the fan B. The pivot axis of the blade 61 preferably passes through the center of gravity of the blade or closely adjacent thereto.

As shown in FIGS. 4-6, an actuating means 70 is provided to effect pivotal movement of the blade 61 with respect to the arm 62 between its minimum and maximum air delivery positions. More specifically, the actuating means 70 includes a reciprocable member which cooperates with the blade to effect the pivotal movement thereof.

As illustrated in FIG. 4, the actuating means 70 includes a member 71 forming a container for a thermally expansible and contractible substance and having cylinder portions 72 cooperating with piston members 73. The piston member's reciprocate in the cylinders 72 to effect the pivotal movement of the blades 61 in response to expansion and contraction of the substance resulting from temperature changes. The member 71 is an annular, tubular member which co-extends with the flange portion 65 of the support member 60 and is suitably secured thereto. The cylinder portions 72 extend in generally radial directions from the member 71 and correspond in number to the number of fan blades 61. The annular member 71 forms a tubular chamber which is filled with a material such as a thermostatic wax, or similar fluid substance, which is operable to expand and contract a substantial amount in response to temperature changes. The member 71, because of its position on the flange portion 65 of the support member 60, is exposed to the flow of air passing across the fan so that the substance in the member 71 expands or contracts in response to changes in temperature of the air flow. I

The cylinder portions 72 open into the tube 71 and are constructed to slidably receive the piston members 73 therein. Each piston member 73 is reciprocable in a generally radial direction relative to the axis of rotation of the fan B in the cylinder portion 72 in response to expansion and contraction of the substance in the member 71. The piston member 73 is linked to the fan blade 61 by a connecting rod 74 such that upon movement of the piston member 73 in response to temperature changes of the substance in the tube 71, the blade 61 is moved between its minimum and maximum delivery positions.

The piston member 73 is a generally cylindrical member engaged on a front face thereof by the thermostatic wax or material contained in the tube 71. The exterior periphery of the cylindrical periphery of the piston member 73 is snugly received by the cylinder portion 72 so that the material in the tube 71 will not leak as the piston is moved in a radial direction relative to the fan B. A spring 76 is disposed in the cylindrical portion 72 and seated against a cap member 77, threaded on the outer periphery of the cylindrical portion 72. The spring 76 engages the rear face of the piston member 73 and urges the piston member 7 3 toward the annular tube 71.

An opposite end 81 of the connecting rod 74 is suitably connected to the fan blade 61 so that upon reciprocation of the piston member 73, the blade 61 of the fan is pivoted as described. The connection between the end 81 of the connecting rod and the blade 61 may be of any suitable type and has not been shown in detail.

As the temperature of the air passing across the fan B increases, the piston member 73 is moved radially outwardly in response to expansion of the material in the tube 71. The connecting rod 74 moves the blade 61 about the pivot axis thereof. When the blade is in its radially extended or maximum delivery position, further rotational movement of the blade is prevented by engagement of the arm 62 and the walls of an indented portion 90 of the blade. Suitable means, not shown, is provided to compensate for overtravel of the piston member in the event that the air temperature continues to increase when the blade 61 is in its maximum delivery position.

Since the fan blade 61 is mounted approximately at its center of gravity, the force exerted thereon by the connecting rod 74 to change the position of the blade is not large so that the connecting rod need not be constructed from heavy material.

As the cooling requirements of the engine decrease, the temperature of the air passing across the fan B decreases accordingly. The material in the tube 71, of course, contracts in response to the decreasing air temperature and the piston member 73 moves radially inwardly as a result of contraction of the material in the tube 71 and the bias of the spring 76. Radially inward movement of the piston member 73 and connecting rod 74 actuate the fan blade from its radially extended position to its radially retracted position.

It should be apparent from the description of the temperature-responsive actuating means that the blade 61 may assume any position intermediate the maximum and minimum delivery positions thereof depending upon the engine cooling requirements as reflected in the temperature of the air passing across the fan B.

It can now be seen that a new and improved fan mechanism has been provided which is operable to provide a varying amount of cooling air fiow for an internal combustion engine and wherein the amount of cooling air provided by the fan is varied in-response to cooling requirements of the engine as reflected in the temperature of the air passing across the fan.

While two preferred embodiments of the present invention have been shown and described herein in considerable detail, the present invention is not to be considered to be limited to the precise constructions shown. For example, a fan embodying the present invention could be constructed using blades having a permanent unbalance, that is, with the center of gravity of the blades'slightly offset from the pivot axis of the blades, and a temperatureresponsive spring or bimetal element for moving the blades between their radially extended and retracted positions. It is my intention to cover hereby all adaptations, modifications, and uses of a fan mechanism embodying the present invention which come within the scope of the appended claims.

Having described my invention, I claim:

1. A fan mechanism for providing a flow of air in response to rotation thereof comprising a support member rotatable about an axis, a blade member movable upon rotation of said support member to create a flow of air,

connecting means between said blade member and said support member providing for pivotal movement of said blade member relative to said support member about an axis parallel to the axis of rotation of said support member between a first position wherein said blade member is operable to provide a first flow of air at a given speed of rotation of said support member and a second position wherein said blade member is operable to provide a second flow of air different from said first flow at said speed of rotation, and temperature-responsive means operable to effect pivotal movement of said blade about said axis parallel to the axis of rotation of said support member from said first to said second position.

2. A fan mechanism as defined in claim 1 wherein said connecting means comprises a pivot pin defining said axis parallel to the axis of rotation of said support member, and said temperature-responsive means includes a member movable in opposite directions in response to temperature changes and operatively connected to said blade offset from the axis defined by said pivot pin to provide for movement of said blade between said positions in response to movement of said member.

3. A fan mechanism for providing a fiow of air in response to rotation thereof comprising a support member rotatable about an axis, a blade member movable upon rotation of said support member to create a flow of air, connecting means between said blade member and said support member providing for movement of said blade member relative to said support member between a first position wherein said blade member is operable to provide a first flow of air at a given speed of rotation of said support member and a second position wherein said blade member is operable to provide a second flow of air different from said first flow at said speed of rotation, and temperature responsive means operable to provide for movement of said blade from said first to said second position, and wherein said blade member is pivotally movable between said positions about an axis extending through the center of gravity of said fan blade and substantially parallel to said axis of rotation of said fan.

4. A fan mechanism for providing a flow of air in response to rotation thereof, comprising a support member rotatable about an axis, a blade member movable upon rotation of said support member to create of flow of air, connecting means between said blade member and said support member providing for movement of said blade member relative to said support member between a first position wherein said blade member is operable to provide first flow of air at a given speed of rotation of said support member and a second position wherein said blade member is operable to provide a second flow of air different from said first flow at said speed of rotation, and temperature responsive means operable to provide for movement of said blade from said first to said second position, said temperature responsive means including a member movable in opposite directions in response to temperature changes and operatively connected to said blade to provide for movement of said blade between said positions in response to movement of said member, said temperature responsive means being carried by said blade and moving therewith, and wherein centrifugal force acting on said movable member is effective to move said blade from said second to said first position when said member is in a first position and from said first to said second position when said movable member is in a second position, and said movable member varies the position of the center of gravity of said member and blade when it moves.

5. A fan mechanism for providing a flow of cooling air comprising a support member rotatable about an axis, a fan blade member connected thereto for rotation therewith, said blade member being connected to said support member for movement relative thereto between a first radially extended position wherein said fan provides a first flow of air and a second position wherein said fan provides a second flow of air less than said first flow at any given fan speed, and actuating means for effecting movement of said fan blade from said first position to said second position and from said second position to said first position, said actuating means including a member movable in opposite directions to effect said movement of said blade, said member being movable between a first position wherein said blade member is moved from said first to said second position thereof and a second position wherein said blade is moved from said second to said first position, and said blade member is pivotally connected to said support member at substantially the center of gravity of said blade member and is moved between said positions in response to centrifugal force.

6. A fan mechanism as defined in claim wherein said movable member is carried by said blade and is acted upon by centrifugal force in one of its said positions to effect pivoting of said blade member in a first direction and is acted upon by centrifugal force in the other of its positions to effect pivoting of said blade member in an opposite direction.

7. A fan mechanism for providing a flow of cooling air comprising a support member rotatable about an axis, blade means movable upon rotation of said support member to create a flow of air, connecting means between said blade means and said support member providing for movement of said blade means relative to said support member in response to centrifugal force between a first position wherein said blade means is operable to provide a large flow of air at a given speed of rotation of said member and a second position wherein said blade means is operable to provide a small flow of air at said speed of rotation, and said blade means including actuating means for shifting the center of gravity of said blade means to eifect movement of said blade means between said first and second positions.

8. A fan mechanism as defined in claim 7 wherein said blade means includes a fan blade member pivotally connected to said support member for pivotal movement about an axis and said actuating means shifts the center of gravity relative to said axis to effect said movement in opposite directions.

9. A fan mechanism as defined in claim 7 wherein said fan mechanism includes a plurality of said fan blade means pivotally connected to said support member at a central portion thereof, with said blades forming substantially a toroid when in their said second position.

10. A fan mechanism as defined in claim 7 wherein said actuating means comprises a temperature responsive means operative to shift said center of gravity in response to temperature changes of air passing across said fan.

11. A fan mechanism as defined in claim 7 wherein said blade means is connected to said support member for pivotal movement about an axis extending gene-rally parallel to said axis of rotation of said support member, and said actuating means includes a member movable in response to temperature changes to effect movement of the blade about said pivot axis.

12. A fan mechanism for providing a flow of air in response to rotation thereof comprising a support member rotatable about an axis, a blade member movable upon rotation of said support member to create a flow of air, means connecting said blade member and said support member and providing for movement of said blade member relative to said support member between a first position wherein the blade member is operable to provide a first flow of air at a given speed of rotation of the support member and a second position wherein said blade member is operable to provide a second flow of air different from the first flow of air at said speed of rotation, and a temperature responsive means operable to effect movement of said blade between said first and second positions, said temperature responsive means comprising a temperature responsive material which expands or contracts upon a temperature change and a mechanism actuated by the expansion and contraction of the material to effect movement of said blade between its positions, and said tem perature responsive material and said mechanism being entirely supported and carried by said blade and movable With said blade.

References Cited UNITED STATES PATENTS MARTIN P. SCHWADRON, Primary Examiner. EVERETTE A. POWELL, JR., Examiner. 

1. A FAN MECHANISM FOR PROVIDING A FLOW OF AIR IN RESPONSE TO ROTATION THEREOF COMPRISING A SUPPORT MEMBER ROTATABLE ABOUT AN AXIS, A BLADE MEMBER MOVABLE UPON ROTATION OF SAID SUPPORT MEMBER TO CREATE A FLOW OF AIR, CONNECTING MEANS BETWEEN SAID BLADE MEMBER AND SAID SUPPORT MEMBER PROVIDING FOR PIVOTAL MOVEMENT OF SAID BLADE MEMBER RELATIVE TO SAID SUPPORT MEMBER ABOUT AN AXIS PARALLEL TO THE AXIS OF ROTATION OF SAID SUPPORT MEMBER BETWEEN A FIRST POSITION WHEREIN SAID BLADE MEMBER IS OPERABLE TO PROVIDE A FIRST FLOW OF AIR AT A GIVEN SPEED OF ROTATION OF SAID SUPPORT MEMBER AND A SECOND POSITION WHEREIN SAID BLADE MEMBER IS OPERABLE TO PROVIDE A SECOND FLOW OF AIR DIFFERENT FROM SAID FIRST FLOW AT SAID SPEED OF ROTATION, AND TEMPERATURE-RESPONSIVE MEANS OPERABLE TO EFFECT PIVOTAL MOVEMENT OF SAID BLADE ABOUT SAID AXIS PARALLEL TO THE AXIS OF ROTATION OF SAID SUPPORT MEMBER FROM SAID FIRST TO SAID SECOND POSITION. 